1. Field of the Invention
The invention relates generally to controllers for controlling the cyclical operation of a plurality of machine components. More specifically, the invention relates to computer based timing and control of the plurality of components in each section of a multi-section glassware forming machine.
2. Description of the Prior Art
Electronic timing or control systems are well known for the control of a plurality of components of a machine. In some machines the components are arranged in a plurality of identical sections, each operating independently of the others in predetermined phase relationship relative to the machine cycle. Prior art electronic control systems have controlled the operation of such sections as a unit and have consequently required use of a single central processing unit (CPU) or supervisory controller connected in hierarchical fashion to a plurality of section controllers. A disadvantage of such systems is that a malfunction of the central controller of the hierarchy prevents operation of any subordinate section controllers.
An example of a multi-section machine of this type is the well-known individual section (IS) glassware forming machine. Electronic timing systems for glassware forming machines have been used for many years in place of mechanical, rotating timing drums. The old timing drums control the actuation of the various components within each section of the machine by actuating associated pneumatic valves with cams placed in circumferential grooves on the drum surface. Electronic timing systems replaced the rotating drum and cams with a solenoid actuated valve block (such as that disclosed in U.S. Pat. No. 3,918,489 assigned to the assignee of the present invention) and control means for actuating selected valves at predetermined times in a predetermined sequence relative to a machine cycle reference point. One major advantage of electronic timing systems is the ease with which the timing settings of the various components may be adjusted during machine operation.
Some prior art IS machine electronic timing systems use timing pulse generators and counters to count pulses occurring during the machine cycle and compare the current count to preset counts to determine when each component or machine event should be actuated (for example, U.S. Pat. No. 3,762,907). Other prior art electronic timing systems use similar count comparisons, but store the preset component timing settings (or machine events) in a core memory (for example, U.S. Pat. No. 3,974,432). Each device disclosed in these two prior art patents serves to control actuation of all section components within the machine but does not provide for independent control of each section.
Programmable automatic machine controllers are also known in the prior art as shown in U.S. Pat. No. Re. 29,642. This controller, however, utilizes a central machine console to couple data to and from each individual section memory unit, thus also preventing totally independent section operation. A similar centrally oriented system, but one incorporating feedback sensors and means for varying the duration of all events in response thereto, is shown in U.S. Pat. No. 4,108,623.
Another type of programmable prior art controller is disclosed in U.S. Pat. No. 4,152,134. This device is limited because it requires a central, machine supervisory computer to load control program and timing data into individual section computers. A malfunction in the machine supervisory computer would affect efficient operation of the sections of the machine.
Yet another programmable controller is disclosed in U.S. Pat. No. 4,247,317 which shows one way to store event timing data in a random access memory and means to alter same. This device uses a central console to control the relative timing of each section which effectively ties all section computer-memory controllers together into one hierarchical machine control system incapable of truly independent section operation.
U.K. Patent Specification No. 1,594,532, assigned to the assignee of the present invention, discloses a prior art electronic control system which utilizes independent, asynchronous clock signals which are produced at a rate independent of the speed of the glassware forming machine. The system disclosed is also for the control of a machine rather than a section.
Other examples of electronic controllers using one computer to control all sections of a machine are disclosed in U.S. Pat. Nos. 3,877,915 and Re. 29,188, assigned to the assignee of the present invention.
U.K. Patent GB No. 2,022,870B discloses a control system with one memory controller controlling each section of a machine. Even if this memory controller is implemented by a microcomputer (as is disclosed in the patent) the microcomputer merely emulates the memory controller's function and the necessary result is a simplistic cycling of the memory controller through a predetermined sequence of steps. There is no means disclosed for enabling modification of this predetermined sequence of steps at the section level in response to operator control. While the operator may adjust timing, there is no disclosure of means by which the operator could change the actual sequence of steps at the section level. Furthermore, the U.K. patent discloses a device necessitating a hierarchical computer or some other external type of loading mechanism for loading a control program. This is a limitation of the independence of the machine sections because they are dependent on an external loading device. Furthermore, this U.K. patent does not disclose means for controlling auxiliary machine functions.
All of the above prior art patents generally disclose a control system architecture comprising a "machine" controller and a plurality of subordinate "section" controllers. Such prior art devices therefore have the disadvantage of either requiring external devices to load control program data or of causing a shut down or inefficient operation of the entire machine in the event the main supervisory computer goes down.
Accordingly, there is a need for an individual section, independent programmable controller capable of independent control of each section of a machine. Such an independent structure would enable simultaneous operation of some or all sections of a machine and permit repairs of selected section controllers without affecting the operation of other sections or necessitating shutting down the entire machine.
The operation of prior art IS machines generally necessitates the operation of several desirable auxiliary or machine functions which are common to all sections although not required for the operation of any one section. Auxiliary function controls include, for example, controls for drive systems (controlling feeders, shears, gob distributors, conveyors, ware transfer devices, etc.), alarms (to signal warnings or malfunctions), shear spray (to lubricate and cool gob shears), cullet water and equipment, stackers (for lehr loading), surface coating equipment, etc. The operation of these auxiliary functions is somewhat related to the operation of the sections of the machine although each section can operate independently of the auxiliary functions.
Aforementioned U.S. Pat. No. 4,152,134 discloses the auxiliary function of selective bottle rejection. However, the machine supervisory computer disclosed in that patent provides the necessary link between each individual section and the bottle reject device. A malfunction of the machine supervisory computer would sever this link for all sections, thus preventing operation of this or other auxiliary functions with any section. Additionally, similar disadvantages arise when peripheral data input/output devices (such as keyboards, tape storage units or alphanumeric displays) are interfaced with the several sections through a hierarchical control structure.
Accordingly, it is another object of this invention to provide a control system to enable individual section independent control while also enabling isolated data communication between selected independent section controllers and selected peripheral data input/output units including auxiliary function devices.